/Engine/Source/Editor/CurveEditor/Public/Views/SInteractiveCurveEditorView.h
Pre-defined layer offsets for specific curve view elements. Fixed values are used to decouple draw order and layering Some elements deliberately leave some spare layers as a buffer for slight tweaks to layering within that element
namespace CurveViewConstants { namespace ELayerOffset { enum { Background = 0, GridLines = 1, GridOverlays = 2, GridLabels = 3, Curves = 10, HoveredCurves = 15, Keys = 20, SelectedKeys = 30, Tools = 35, DragOperations = 40, Labels = 45, WidgetContent = 50, Last = Labels, } } }